Containers with tubing are used for various medical procedures such as kidney dialysis, intravenous delivery of therapeutic fluids, delivery of nutritional fluids; delivery of blood, blood components, and blood substitutes. Particularly in blood banking connections are frequently used between the containers and associated tubing. Such applications may require connecting two or more different containers to one another each of which typically contains a different sterile material. For example, in the blood-banking environment, a bag containing sterile solution may be connected to an apheresis kit containing tubing. Regardless of any particular application, in most cases connections between two tubes are formed.
Connecting the tubing typically involves using a sterile tube welding machine to weld the thermoplastic tubing in a sterile manner. There are many sterile tube welding machines known to one skilled in the art. One type of tube welding machine sterilizes a cutting blade or wafer then moves the blade through the two ends of the tubing to be joined. Once both ends of the tubing have been cut, the machine aligns the ends of the tubes while maintaining a high temperature. After the thermoplastic tubes cool, a sterile weld is formed. Other tube connection systems have applied heat to the ends of the tubing sections without requiring direct contact of heating elements with the tubing sections. See, for example, U.S. patent application Ser. No. 10/061,835, filed Jan. 31, 2002; Ser. No. 10/251,681, filed Sep. 20, 2002; Ser. No. 10/251,682, filed Sep. 20, 2002; and Ser. No. 10/251,683, filed Sep. 20, 2002, all of which are incorporated herein by reference in their entirety. Regardless of the type of tube welding device utilized, connecting the ends of the tube sections requires a precise alignment of the tube ends due to the relatively small wall thickness of the tube.
Sterile tube welding devices may have a relatively low level of reliability due to the inconsistency in aligning the tube ends following the melting and cutting processes. The inconsistency of operation can result in imperfect seals, leading to leaks, and microorganism infiltration which may lead to infection. In addition, the interior passages of the tubing sections are initially sterile, but in some instances cutting the tubing sections so that connections of adjacent sections can be made exposes the interior passages of the tubing sections to the surrounding environment, allowing them to potentially become contaminated with airborne contaminants, e.g., bacteria. In order to avoid exposure of the interior passage (i.e., lumen) of each tubing section, some tube welding devices clamp the end portion of the tubing section shut before an end portion of the tubing section is cut.
In some systems a hot blade or other heated surface is brought into contact with the tubing sections to bring them up to melting temperature. The ends of the two tubing sections are then brought together so that the melted ends fuse, connecting the tubing sections together. The clamps collapsing the respective end portions of the tubing sections are released and the tubing sections open, defining a continuous, sealed interior passage through the connected tubing sections. Unfortunately, the connection must often be manually opened and/or examined to ensure proper seal, thereby increasing the time and labor.
For tube welding devices that utilize a hot plate for producing molten thermoplastic and welding molten tubes, another disadvantage is that in time the hot plate becomes fouled with the plastic material, e.g., some thermoplastic resin may adhere to the hot plate, requiring occasional cleaning of the hot plate to maintain sterile operating conditions or using disposable cutting blades, thereby increasing the overall time and cost.
Accordingly, there is a need for various improvements in thermoplastic tube weld connecting devices.